licht.wissen No. 01 "Lighting with Artificial Light"

licht.wissen 01
Lighting with Artificial Light
Light generation in the 21 st century
LEDs have revolutionized lighting in recent years. New and efficient technologies are increasingly replacing
the old thermal radiators.
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of use
The relative importance of different types of
light generation has shifted dramatically in
recent years: incandescent light bulbs, even
in the form of halogen lamps, are on the
decline. Fluorescent lamps and other gas
discharge lamps are also increasingly being
replaced by LED technology – in the form
of retrofit lamps, modules or complete systems.
Why the change?
The generation of artificial light requires
energy: 15 percent of electric power worldwide
is still used for lighting (IEA/UNEP,
spring 2014). Which is why any efforts to
reduce energy consumption always involves
lighting savings. The photometric
requirements for each application must
nevertheless be met (such as minimum
illuminance at work), as these are often
safety-related, and thus also of legal significance.
Governments are applying great pressure
in order to save light-related energy; the
European Union (EU) has introduced directives
aimed at increasing energy efficiency.
Light sources that do not meet these requirements
may no longer be marketed as
new products in the EU. In addition, end
users are informed by corresponding markings
on the energy labels showing which
light sources are highly efficient (A++ with
green arrow = “desirable”) and which are
particularly inefficient (E with red arrow =
“Warning, not desirable”). Similar arrangements
now also apply in other countries
outside the EU.
technology must effect a major change if
they wish to remain successful in the
market. However, efficiency is not everything:
besides generating brightness, light
also needs to meet other requirements
(see “Quality characteristics of lighting”,
page 15).
At the same time the applications are becoming
increasingly complex, which is why
there is now strong demand for professionals
in the planning, implementation and
operation of good lighting systems. This is
giving rise to new opportunities because
there is now an increased focus on controllability,
and thus also the question of what
“language” the components use to speak
with one another; should DALI components
be integrated into a bus system or is wireless
control preferable?
Colour? Dimming? It is the user who decides
how elaborate the system should be
and how it is ultimately controlled: preprogrammed
and then automatically controlled,
or by APP, by switch or remote
control.
Light generation – traditional:
Incandescent and halogen lamps
Incandescent and halogen lamps are thermal
radiators in which light is generated by
heating the tungsten filament wire. The
glass bulb can be evacuated or filled with
gas – generally with noble gas(es) or nitrogen.
Incandescent lamps have low luminous
efficacy, but they offer perfect colour
rendering and are fully dimmable.
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© licht.de
[59] The energy label for lamps (as of
September 2013) provides information on
the efficiency classes of light sources. LEDs
and energy saving lamps are especially
efficient.
[60] Efficient and elegant. The curved OLED
ceiling lamp provides pleasant, glare-free
light.
What does this change mean
in practice?
Light sources and lamps based on less
energy-efficient technologies are either no
longer produced as a direct result of the
directives or are losing their attraction to
such an extent that they are no longer used
– regardless of any other benefits they may
have. Thus, manufacturers which previously
worked mainly with traditional lighting
However, the luminous efficacy can be increased
by means of double coiling and/or
refinement of the gas filling, e.g. through
the addition of krypton or xenon. Halogens
reduce the evaporation of tungsten from
the filament, thereby preventing bulb blackening
in halogen lamps. Further efficiency
gains can be obtained through the use of
infrared (IR) reflective coatings of the glass
bulb.
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